| Lake pollution received extensive attention in recent years. Particularlly, eutrophication resulting in cyanobacteria bloom in the lakes in the middle and lower Yangtze River floodplain has become a serious environmental problem, threating the security of regional ecological systems. The lake eutrophication, becoming a major factor hampering economic and social sustainable development, is a serious national environmental problem. The Chaohu Lake is one of the most serious eutrophication lakes in China. Caizi Lake is less affected by industrial pollution relatively, and had less eutrophication. Inevitably, organisms are affected adversely, and the residents relying on the lakes for water supply are threatened, either. It is very important to control of the water pollution. Whereas, evaluating water quality precisely is the premise of water pollution control. The toxic effects of polluted water on organisms could reflect the condition of water pollution. So, using organisms to monitor water pollution would supplement the routine water monitoring.In this study, Chaohu Lake and Caizi Lake two different eutrophic lakes along the Yangtze River in Anhui Province were chosed as our study area, and Procambarus clarkii as target species to assess the toxic effects of the pollutants in the two lakes. DNA damages and micronucleus ratios of haemocytes of Procambarus clarkii detected by comet assay and micronucleus test, seasonal variation of genotoxicity and the correlation between water eutrophic and genotoxicity were analyzed to evaluate the pollution of the two lakes. The results were as follows.(1) In Chaohu Lake and Caizi Lake, the lowest micronucleus ratios of haemocytes of Procambarus clarkii in April were 0.316±0.131 and 0.243±0.063 respectively, and the highest values in November were 0.691±0.057 and 0.394±0.017 respectively. The lowest values of the three indicators of DNA damage, JailDNA,TM and OTM were 2.34±0.88,0.36±0.22 and 0.52±0.20 respectively in Chaohu Lake, and 1.92±1.98,0.35±0.33 and 0.51±0.27 respectively in Caizi Lake. The highest values were 8.92±1.73,3.94±0.17,4.63±1.62 in Chaohu Lake, and 6.17±0.20, 1.54±0.03, 1.63±0.13 in Caizi Lake respectively. The highest values of micronucleus ratios and DNA damage appeared in November and the lowest values appeared in April. Micronucleus ratios and DNA damage had an increasing tendency frome April to November in the two lakes, indicating that the genotoxicity enhanced as the time changed and there were different pollution in the two lakes(2) The higher eutrophic Chaohu Lake was detected to have higher genotoxicity than the lower eutrophic Caizi Lake. Micronucleus ratios and DNA damage reached significant differences (P< 0.01) from July to November between the two lakes. In June, DNA damage reached differences (0.01< P< 0.05) between the two lakes. There has the higher genotoxicity on Procambarus clarkii and it contains the higher concentration of genetic toxic pollutants in Chaohu Lake.(3) In the early period of cyanobacterial bloom June and July, DNA damage and micronucleus ratios increased significantly in Chaohu Lake, which indicates increased genotoxicity to Procambarus clarki. DNA damage reached significant differences (P<0.01) between May and June, June and July, and micronucleus ratios reached differences (0.01<P<0.05) between June and July. In June and July, the genetic toxicity of Procambarus clarkii increased greatest in Chaohu Lake. But there did not have the similar tendency in Caizi Lake. So, we thought that genotoxicity significantly increased in the early period of cyanobacterial bloom maybe related with Chaohu Lake eutrophic.(4) Detection results were the same for the two different tests, but comet assay is more sensitive then micronucleus test. So we suggest that it's necessary to combine the two tests to get more effective detection of genetic toxicity.Genetic toxicity of Chaohu Lake has obvious seasonal characteristics, so it is suggested to pay more attention on the water quality during the period of cyanobacterial bloom. |
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